1. Field of the Invention
The present invention generally relates to a mobile terminal, and more particularly to a system and method for providing power to a mobile terminal.
2. Description of the Related Art
As mobile terminals provide users with enhanced services such as music, video, and games in addition to simple voice communications, data transmission and reception at faster rates and higher quality has become a critical matter. In order to quickly transmit large amounts of data, data transmission/reception methods which use a USB connection unit (interface) such as a USB port or a USB cable has become widely used.
FIG. 1 shows one type of power supply apparatus which has been proposed for use in a general terminal. This apparatus includes a voltage power (VPWR) 10 which powers operation of the terminal. The VPWR provides operation power from a battery typically in the range of 3.3-4.2 volts.
Power supplied by the VPWR is usually changed to about 2.5-12V by a low drop output (LDO) regulator 11 and this power level is then supplied to each part of the terminal. In general, 2.7V is supplied to a modem (MSM) 12 of the terminal, 2.7V to a receiving part (Rx part), 3.0V to an intermediate frequency unit and transmitter, 3.3V to an audio part, and 5.0V to a light emitting diode (LED).
While a carrier voltage for transmission of data supplied through a USB cable 13 from the USB power supply apparatus 15 is 5.0V, an MSM actuation voltage has a different value of usually 2.7V To resolve this difference, a USB transceiver 14 is generally used to match the transmission voltage of the USB cable 13 with the actuation voltage. A current signal including data information input through the USB cable 13 is matched by the USB transmitter/receiver 14, so that the carrier voltage is discarded and only data is transmitted to the MSM 12 by the MSM actuation voltage.
However, although a voltage of 5.0V is supplied through the USB cable 13, the USB transmitter/receiver 14 and the MSM 12 are in a disconnected state until the terminal system is booted by the VPWR 10, so communication with the terminal through the USB cable 13 is not possible. That is, in order to upload data from the USB interface to the terminal or download it, a power supply apparatus such as a battery or a mobile charger is necessary, since without it, it is not possible to transfer data or an information signal through the USB interface.